mirror of https://github.com/JDAI-CV/fast-reid.git
98 lines
3.3 KiB
Python
98 lines
3.3 KiB
Python
# encoding: utf-8
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"""
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@author: xingyu liao
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@contact: liaoxingyu5@jd.com
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"""
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import torch
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import torch.nn.functional as F
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from torch import nn
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from torch.nn import Conv2d, ReLU
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from torch.nn.modules.utils import _pair
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from fastreid.layers import get_norm
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class SplAtConv2d(nn.Module):
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"""Split-Attention Conv2d
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"""
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def __init__(self, in_channels, channels, kernel_size, stride=(1, 1), padding=(0, 0),
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dilation=(1, 1), groups=1, bias=True,
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radix=2, reduction_factor=4,
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rectify=False, rectify_avg=False, norm_layer=None, num_splits=1,
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dropblock_prob=0.0, **kwargs):
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super(SplAtConv2d, self).__init__()
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padding = _pair(padding)
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self.rectify = rectify and (padding[0] > 0 or padding[1] > 0)
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self.rectify_avg = rectify_avg
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inter_channels = max(in_channels * radix // reduction_factor, 32)
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self.radix = radix
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self.cardinality = groups
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self.channels = channels
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self.dropblock_prob = dropblock_prob
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if self.rectify:
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from rfconv import RFConv2d
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self.conv = RFConv2d(in_channels, channels * radix, kernel_size, stride, padding, dilation,
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groups=groups * radix, bias=bias, average_mode=rectify_avg, **kwargs)
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else:
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self.conv = Conv2d(in_channels, channels * radix, kernel_size, stride, padding, dilation,
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groups=groups * radix, bias=bias, **kwargs)
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self.use_bn = norm_layer is not None
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if self.use_bn:
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self.bn0 = get_norm(norm_layer, channels * radix, num_splits)
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self.relu = ReLU(inplace=True)
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self.fc1 = Conv2d(channels, inter_channels, 1, groups=self.cardinality)
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if self.use_bn:
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self.bn1 = get_norm(norm_layer, inter_channels, num_splits)
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self.fc2 = Conv2d(inter_channels, channels * radix, 1, groups=self.cardinality)
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self.rsoftmax = rSoftMax(radix, groups)
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def forward(self, x):
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x = self.conv(x)
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if self.use_bn:
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x = self.bn0(x)
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if self.dropblock_prob > 0.0:
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x = self.dropblock(x)
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x = self.relu(x)
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batch, rchannel = x.shape[:2]
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if self.radix > 1:
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splited = torch.split(x, rchannel // self.radix, dim=1)
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gap = sum(splited)
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else:
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gap = x
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gap = F.adaptive_avg_pool2d(gap, 1)
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gap = self.fc1(gap)
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if self.use_bn:
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gap = self.bn1(gap)
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gap = self.relu(gap)
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atten = self.fc2(gap)
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atten = self.rsoftmax(atten).view(batch, -1, 1, 1)
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if self.radix > 1:
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attens = torch.split(atten, rchannel // self.radix, dim=1)
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out = sum([att * split for (att, split) in zip(attens, splited)])
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else:
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out = atten * x
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return out.contiguous()
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class rSoftMax(nn.Module):
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def __init__(self, radix, cardinality):
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super().__init__()
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self.radix = radix
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self.cardinality = cardinality
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def forward(self, x):
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batch = x.size(0)
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if self.radix > 1:
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x = x.view(batch, self.cardinality, self.radix, -1).transpose(1, 2)
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x = F.softmax(x, dim=1)
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x = x.reshape(batch, -1)
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else:
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x = torch.sigmoid(x)
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return x
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